Flying birds and swimming fish are familiar sights to everyone, but their remarkable behaviors and abilities are often poorly understood. Inspired by animal locomotion found in nature, we discuss two recent laboratory experiments on interactions between dynamic boundaries (for example, flapping wings or fins) and moving fluids. In the first experiment, we study the physical origin of flapping flight and the role played by wing flexibility in determining flight speed and also direction. In the second experiment, we investigate the group dynamics of multiple locomotors as they interact with each other through the surrounding flows. Many of the surprising results from these laboratory studies might reshape one's "common sense" on animal flight and swimming.